The use of robots is widespread in the semiconductor industry, due to their ability to process a large number of semiconductor wafers through many different processing technologies, and to perform repetitive tasks quickly and accurately. The use of robots is especially advantageous in portions of semiconductor fabrication lines where human handling of semiconductor wafers is inefficient or undesirable. For example, many semiconductor fabrication processes, such as etching, deposition, and passivation, occur in reaction chambers having sealed environments. The use of robots allows these environments to be carefully maintained in order to minimize the likelihood of contamination and to optimize processing conditions.
Modern semiconductor processing systems include cluster tools that integrate a number of process chambers together in order to perform several sequential processing steps without removing the substrate from the highly controlled processing environment. These chambers may include, for example, degas chambers, substrate pre-conditioning chambers, cool-down chambers, transfer chambers, chemical vapor deposition chambers, physical vapor deposition chambers, and etch chambers. The combination of chambers in a cluster tool, as well as the operating conditions and parameters under which those chambers are run, are selected to fabricate specific structures using a specific process recipe and process flow.
Once the cluster tool has been set up with a desired set of chambers and auxiliary equipment for performing certain process steps, the cluster tool will typically process a large number of substrates by continuously passing them, one by one, through a series of chambers or process steps. The process recipes and sequences will typically be programmed into a microprocessor controller that will direct, control and monitor the processing of each substrate through the cluster tool. Once an entire cassette of wafers has been successfully processed through the cluster tool, the cassette may be passed to yet another cluster tool or stand alone tool, such as a chemical mechanical polisher, for further processing.
One example of a known fabrication system of the type described above is the cluster tool 101 disclosed in U.S. Pat. No. 6,222,337 (Kroeker et al.), and reproduced in FIGS. 1-2 herein. The magnetically coupled robots 103, 153 disclosed therein are equipped with upper 105 and lower 107 robotic arms having a frog-leg type construction that are adapted to provide both radial and rotational movement of the robot blade 109 within a fixed plane. The radial and rotational movements can be coordinated or combined to allow for pickup, transfer and delivery of substrates from one location within the cluster tool to another location. For example, the robotic arm may be used to move substrates from one processing chamber to an adjacent chamber.
FIG. 1 is a schematic diagram of the integrated cluster tool 101 of Kroeker et al. Wafers or other substrates 102 are introduced into, and withdrawn from, the cluster tool 101 through a cassette loadlock 111. A robot 103 having a blade 109 is located within a chamber 113 of the cluster tool 101 and is adapted to transfer the substrates from one process chamber to another. These process chambers may include, for example, a cassette loadlock 115, a degas wafer orientation chamber 117, a preclean chamber 119, a PVD TiN chamber 121 and a cooldown chamber 123. The robot blade 109 is illustrated in the retracted position in which it can rotate freely within the chamber 113.
A second robot 153 is located in transfer chamber 163, and is adapted to transfer substrates between various chambers which may include, for example, a cool-down chamber 165, a pre-clean chamber 167, a CVD Al chamber 169 and a PVD AlCu processing chamber 171. The specific configuration of chambers illustrated in FIG. 1 is designed to provide an integrated processing system capable of both CVD and PVD processes in a single cluster tool. A microprocessor controller 171 is provided to control the fabricating process sequence, conditions within the cluster tool, and the operation of the robots 103, 153.
Robots of the type depicted in FIGS. 1-2 above are utilized, for example, in the ENDURA® and CENTURA® 200 nm/300 nm platforms sold by Applied Materials (Santa Clara, Calif.). As seen in FIG. 2, these robots 103 include a central hub 131, a pair of upper arms 105, and a pair of lower arms 107. The lower arms 107 are rotatingly attached to the hub 131 and are driven by servo drives housed within the hub 103.